Process of and apparatus for cooking wood pulp



(No Model.)

0. GORNWELL.

PROCESS OF AND APPARATUS FOR COOKING WOOD PULP. No. 357,371. Patented Feb. 8, 1887.

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CLARK CORNWELL, OF YPSILANTI, MICHIGAN.

PROCESS OF AND APPARATUS FOR COOKING wooo PULP.

SPECIFICATION forming part of Letters Patent No. 357,371, dated February 8, 1887.

Application filed November 11, 1886. 7 Serial No. 218,607. (No modeh) It has for its object the utilization of the gas arising from the material being cooked in the digester and its continuous return from the top to the bottomof the digester, whereby a constant circulation is kept up through the material being cooked, and the full effect of the gas is obtained during the entire process of cooking.

The novelty of my invention will be herein set forth, and specifically pointed out in the claims. I

In the accompanying drawings, Figure 1 is a central sectional elevation of a digester containing means for carrying out my invention. Fig. 2 is a corresponding view representing a modification in the means employed.

The same letters of reference are used to indicate identical parts in all the figures.

A represents the usual or any suitable digester; B, the man-hole for theintroduction of the wood and liquor; O, the perforated diaphragm near the bottom, on which the wood rests.

In what is known as the bisulphide process, where a sulphurous-acid solution is employeda solution consisting of water, with lime or soda base, charged with sulphurous acid-and which solution is used for cooking and digesting the wood, the liquor when heated gives off its gas, which, escaping into the upper part of the digester, remains a dead quantity, and its beneficial-action in the process of cooking and digesting is lost. I propose to utilize this gas and use it again by conveying it from the top of the digester to the bottom and causing it to circulate up through the pulp and liquor to the top of the digester, whence it is again conveyed to the bottom and passed up as before, thus causing it to continually circulate through and act upon the material being cooked. One means for accomplishing this result automatically is shown-in Fig. 1, where D is a pipe extending from the top of the digester, down through the perforated diaphragm C to a point below the same, where it is connected to an enlarged chamber, E, into which the live-steam pipe F enters in such manner as to form an injector, whereby the gas in the top of the digester is drawn down through the pipe D, and is discharged with the steam beneath the diaphragm O, and at once rises through the cooking mass.

A check-valve, G, is provided infthe pipe D, to prevent the flow of the gas through said pipe, except in a downward direction.

As a modification of the arrangement of the injector and check-valve, and by which a more positive forcing of the gas is, perhaps, effected, the construction shown in Fig. 2 may be employed, where the steam-pipe]? is connected to the pipe D by injector mechanism above the liquor in the digester, and the check-valve is applied to the pipe D above said injector.

It is evident that the gas-pipe D might be brought down on the outside of the digester, if desired, instead of on the inside, as shown in the drawings.

It will be seen that in this way I maintain a constant circulation of the gas through and action upon the contents of the digester.

Having thus fully described my invention, I claim- 1. In the cooking of wood pulp in a digester, the process of continuously conveying the escaping gas from the top of the digester to the bottom thereof and causing it to pass up through the mixture being cooked, substantially as and for the purpose described.

2. The combination, with a digester, of a gas-pipe extending from the upper part of said digester to the lower part thereof, a live-steam pipe connected to said pipe by means of in jector mechanism, and a check-valve in said gas-pipe, whereby the gas in the top of the digester is continuously returned to the bottom thereof and caused to circulate up through the mixture being cooked, substantially as and for the purpose described.

3. The combination, with a digester prodigester is continuously returned to the botvided with a perforated diaphragm near its bottom, of a gas-pipe extending from the upper part of said digester to the lower part 5 thereof beneath the diaphragm, a livesteam pipe connected to said pipe by means of injector mechanism, and a check-Valve in said gas-pipe, whereby the gas in the top of the to n1 thereof and caused to circulate up through IO the mixture being cooked, substantially as and for the purpose described.

CLARK CORNTVELL. Vitnesses:

H. O. SULLIVAN, E. O. CORNWELL. 

